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1.
Nat Commun ; 15(1): 2296, 2024 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-38485971

RESUMO

The connectivity within single carrier information-processing devices requires transport and storage of single charge quanta. Single electrons have been adiabatically transported while confined to a moving quantum dot in short, all-electrical Si/SiGe shuttle device, called quantum bus (QuBus). Here we show a QuBus spanning a length of 10 µm and operated by only six simply-tunable voltage pulses. We introduce a characterization method, called shuttle-tomography, to benchmark the potential imperfections and local shuttle-fidelity of the QuBus. The fidelity of the single-electron shuttle across the full device and back (a total distance of 19 µm) is (99.7 ± 0.3) %. Using the QuBus, we position and detect up to 34 electrons and initialize a register of 34 quantum dots with arbitrarily chosen patterns of zero and single-electrons. The simple operation signals, compatibility with industry fabrication and low spin-environment-interaction in 28Si/SiGe, promises long-range spin-conserving transport of spin qubits for quantum connectivity in quantum computing architectures.

2.
Nat Commun ; 15(1): 1325, 2024 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-38351007

RESUMO

Long-ranged coherent qubit coupling is a missing function block for scaling up spin qubit based quantum computing solutions. Spin-coherent conveyor-mode electron-shuttling could enable spin quantum-chips with scalable and sparse qubit-architecture. Its key feature is the operation by only few easily tuneable input terminals and compatibility with industrial gate-fabrication. Single electron shuttling in conveyor-mode in a 420 nm long quantum bus has been demonstrated previously. Here we investigate the spin coherence during conveyor-mode shuttling by separation and rejoining an Einstein-Podolsky-Rosen (EPR) spin-pair. Compared to previous work we boost the shuttle velocity by a factor of 10000. We observe a rising spin-qubit dephasing time with the longer shuttle distances due to motional narrowing and estimate the spin-shuttle infidelity due to dephasing to be 0.7% for a total shuttle distance of nominal 560 nm. Shuttling several loops up to an accumulated distance of 3.36 µm, spin-entanglement of the EPR pair is still detectable, giving good perspective for our approach of a shuttle-based scalable quantum computing architecture in silicon.

3.
Microbiol Spectr ; : e0053823, 2023 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-37732806

RESUMO

Bacterial cells can vary greatly in size, from a few hundred nanometers to hundreds of micrometers in diameter. Filamentous cable bacteria also display substantial size differences, with filament diameters ranging from 0.4 to 8 µm. We analyzed the genomes of cable bacterium filaments from 11 coastal environments of which the resulting 23 new genomes represent 10 novel species-level clades of Candidatus Electrothrix and two clades that putatively represent novel genus-level diversity. Fluorescence in situ hybridization with a species-level probe showed that large-sized cable bacteria belong to a novel species with the proposed name Ca. Electrothrix gigas. Comparative genome analysis suggests genes that play a role in the construction or functioning of large cable bacteria cells: the genomes of Ca. Electrothrix gigas encode a novel actin-like protein as well as a species-specific gene cluster encoding four putative pilin proteins and a putative type II secretion platform protein, which are not present in other cable bacteria. The novel actin-like protein was also found in a number of other giant bacteria, suggesting there could be a genetic basis for large cell size. This actin-like protein (denoted big bacteria protein, Bbp) may have a function analogous to other actin proteins in cell structure or intracellular transport. We contend that Bbp may help overcome the challenges of diffusion limitation and/or morphological complexity presented by the large cells of Ca. Electrothrix gigas and other giant bacteria. IMPORTANCE In this study, we substantially expand the known diversity of marine cable bacteria and describe cable bacteria with a large diameter as a novel species with the proposed name Candidatus Electrothrix gigas. In the genomes of this species, we identified a gene that encodes a novel actin-like protein [denoted big bacteria protein (Bbp)]. The bbp gene was also found in a number of other giant bacteria, predominantly affiliated to Desulfobacterota and Gammaproteobacteria, indicating that there may be a genetic basis for large cell size. Thus far, mostly structural adaptations of giant bacteria, vacuoles, and other inclusions or organelles have been observed, which are employed to overcome nutrient diffusion limitation in their environment. In analogy to other actin proteins, Bbp could fulfill a structural role in the cell or potentially facilitate intracellular transport.

4.
Mar Pollut Bull ; 194(Pt A): 115276, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37459772

RESUMO

The Baffin Island Oil Spill (BIOS) Project is a long-term monitoring field study conducted in the early 1980s, seeking to examine the physical and chemical fate of crude oil released into a pristine Arctic setting. During the present study, sites of the BIOS Project were revisited in 2019 for the collection of oiled intertidal and backshore sediments. These samples were analyzed for several groups of petroleum hydrocarbons including saturates (n-alkanes, branched alkanes, and alkylcycloalkanes), hopane and sterane biomarkers, and alkylbenzenes. These hydrocarbon groups were present in concentrations ranging from 1.77-1210, 0.224-51.7, 0.0643-16.9, 0.00-11.7, and 0.0171-8.60 mg/kg within individual samples, respectively. When comparing current to limited results from past BIOS studies, a representative branched alkane (phytane), and medium-chain (nC18) and long-chain (nC30) n-alkanes demonstrate extensive weathering processes, exhibiting up to 90 %, 98 %, and 77 % loss since the penultimate BIOS revisitation in 2001, respectively.


Assuntos
Poluição por Petróleo , Petróleo , Poluentes Químicos da Água , Poluentes Químicos da Água/análise , Hidrocarbonetos , Alcanos , Biomarcadores
5.
Environ Res ; 233: 116421, 2023 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-37327845

RESUMO

With an on-going disproportional warming of the Arctic Ocean and the reduction of the sea ice cover, the risk of an accidental oil spill from ships or future oil exploration is increasing. It is hence important to know how crude oil weathers in this environment and what factors affect oil biodegradation in the Arctic. However, this topic is currently poorly studied. In the 1980s, the Baffin Island Oil Spill (BIOS) project carried out a series of simulated oil spills in the backshore zone of beaches located on Baffin Island in the Canadian High Arctic. In this study two BIOS sites were re-visited, offering the unique opportunity to study the long-term weathering of crude oil under Arctic conditions. Here we show that residual oil remains present at these sites even after almost four decades since the original oiling. Oil at both BIOS sites appears to have attenuated very slowly with estimated loss rates of 1.8-2.7% per year. The presence of residual oil continues to significantly affect sediment microbial communities at the sites as manifested by a significantly decreased diversity, differences in the abundance of microorganisms and an enrichment of putative oil-degrading bacteria in oiled sediments. Reconstructed genomes of putative oil degraders suggest that only a subset is specifically adapted for growth under psychrothermic conditions, further reducing the time for biodegradation during the already short Arctic summers. Altogether, this study shows that crude oil spilled in the Arctic can persist and significantly affect the Arctic ecosystem for a long time, in the order of several decades.


Assuntos
Poluição por Petróleo , Petróleo , Petróleo/metabolismo , Ecossistema , Canadá , Regiões Árticas , Biodegradação Ambiental
6.
Environ Res ; 222: 115329, 2023 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-36693458

RESUMO

The Arctic is a unique environment characterized by extreme conditions, including daylight patterns, sea ice cover, and some of the lowest temperatures on Earth. Such characteristics in tandem present challenges when extrapolating information from oil spill research within warmer, more temperate regions. Consequently, oil spill studies must be conducted within the Arctic to yield accurate and reliable results. Sites of the Baffin Island Oil Spill (BIOS) project (Cape Hatt, Baffin Island, Canadian Arctic) were revisited nearly 40 years after the original oil application to provide long-term monitoring data for Arctic oil spill research. Surface and subsurface sediment samples were collected from the intertidal zone of the 1981 nearshore oil spill experiment (Bay 11), from 1980 supratidal control plots (Crude Oil Point) and 1982 supratidal treatment plots (Bay 106). Samples were analyzed for Polycyclic Aromatic Hydrocarbons (PAHs) and alkylated homologues via Gas Chromatography - Mass Spectrometry (GC-MS). Our results suggest that total mean concentrations of all measured PAHs range from 0.049 to 14 mg/kg, whereas total mean concentrations of the 16 US EPA priority PAHs range from 0.02 to 2.1 mg/kg. The relative proportions of individual PAHs were compared between sampling sites and with the original technical mixture. Where available, percent loss of individual PAHs was compared with data from samples collected at the BIOS site, in 2001. All three sites featured samples where concentrations of various priority PAHs exceeded the established Interim Marine Sediment Quality Guidelines. All supratidal samples contained potentially toxic levels of PAHs. Even after nearly four decades of weathering, the recalcitrant crude oil residues remain a potential hazard for the native organisms. Continued monitoring of this unique study site is crucial for establishing a timeline for oil degradation, and to observe a reduction in toxicity over time.


Assuntos
Poluição por Petróleo , Petróleo , Hidrocarbonetos Policíclicos Aromáticos , Poluentes Químicos da Água , Petróleo/análise , Petróleo/metabolismo , Hidrocarbonetos Policíclicos Aromáticos/análise , Canadá , Monitoramento Ambiental/métodos , Poluentes Químicos da Água/análise , Sedimentos Geológicos
7.
J Hazard Mater ; 445: 130439, 2023 03 05.
Artigo em Inglês | MEDLINE | ID: mdl-36437193

RESUMO

The biodegradability of residues derived from in-situ burning, an oil spill response strategy which involves burning an oil slick on the sea surface, has not yet been fully studied. With a growing risk of oil spills, the fate of the persistent burn residue containing potentially toxic substances must be better understood. Microcosms were used to study the microbial community response and potential biodegradability of in-situ burn residues generated from Ultra Low Sulphur (ULS) marine diesel. Microcosm studies were conducted using residues originating from the burning of unweathered and weathered diesel, with the addition of a fertilizer and a dispersant. Burn residues were incubated for 6 weeks at 7 °C in natural seawater with continual agitation in the dark. Samples were subsequently sacrificed for chemistry as well as 16S rRNA gene amplicon and shotgun metagenomic sequencing. Chemistry analyses revealed a reduction in hydrocarbon concentrations. Medium chain-length n-alkanes (nC16-nC24) decreased by 8% in unweathered burn residue microcosms and up to 26% in weathered burn residue microcosms. A significant decrease in polycyclic aromatic hydrocarbon (PAH) concentrations was observed only for naphthalene, fluorene and their alkylated homologs, in the microcosms amended with residue produced from burning weathered diesel. Decreases of 2-24%, were identified depending on the compound. Microcosms amended with burn residues had distinct microbial communities marked by an increase in relative abundance of putative hydrocarbon degraders as well as an increase of known hydrocarbon-degradation genes. These novel results suggest that if in-situ burning is performed on ULS marine diesel, some of the indigenous bacteria would respond to the newly available carbon source and some of the residual compounds would be biodegraded. Future studies involving longer incubation periods could give a better understanding of the fate of burn residues by shedding light on the potential biodegradability of the more recalcitrant residual compounds.


Assuntos
Poluição por Petróleo , Petróleo , Hidrocarbonetos Policíclicos Aromáticos , RNA Ribossômico 16S/genética , Hidrocarbonetos/metabolismo , Água do Mar/microbiologia , Hidrocarbonetos Policíclicos Aromáticos/análise , Poluição por Petróleo/análise , Biodegradação Ambiental , Petróleo/metabolismo
8.
Environ Res ; 216(Pt 1): 114456, 2023 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-36181891

RESUMO

In 1999, a tidal wetland located along the St. Lawrence River close to Ste. Croix de Lotbinière (Quebec, Eastern Canada) was the site of an experimental oil spill. Test plots were established and subjected to an experimental crude oil spill to evaluate natural attenuation, nutrient amendment and vegetation cropping as countermeasures. In 2020, this study re-visited the test plots to investigate residual oil and habitat recovery. Only concentrations of mid-chain length n-alkanes (C10-C36), but not of polycyclic aromatic hydrocarbons (PAHs), were significantly above detection limit, and were detected in both test plot and control sediments. Hydrocarbon, total organic carbon, nitrogen and phosphate contents did not differ significantly between test plot and control sediments. Microbial analyses did not detect significant differences in microbial load, microbial diversity or microbial community composition between test plot and control sediments. Key genes for the aerobic and anaerobic degradation of n-alkanes as well as for the aerobic degradation of PAHs were detected in all sediment samples. Associated gene abundances did not differ significantly between test plot and control sediments. This study shows that oil-exposed test plot sediments of the Ste. Croix wetland can be considered completely recovered after 21 years irrespective of the performed countermeasure.


Assuntos
Microbiota , Poluição por Petróleo , Petróleo , Hidrocarbonetos Policíclicos Aromáticos , Poluentes Químicos da Água , Poluição por Petróleo/análise , Rios , Áreas Alagadas , Petróleo/análise , Sedimentos Geológicos/análise , Poluentes Químicos da Água/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , Alcanos/análise , Monitoramento Ambiental
9.
Brief Bioinform ; 23(6)2022 11 19.
Artigo em Inglês | MEDLINE | ID: mdl-36352504

RESUMO

In shotgun metagenomics (SM), the state-of-the-art bioinformatic workflows are referred to as high-resolution shotgun metagenomics (HRSM) and require intensive computing and disk storage resources. While the increase in data output of the latest iteration of high-throughput DNA sequencing systems can allow for unprecedented sequencing depth at a minimal cost, adjustments in HRSM workflows will be needed to properly process these ever-increasing sequence datasets. One potential adaptation is to generate so-called shallow SM datasets that contain fewer sequencing data per sample as compared with the more classic high coverage sequencing. While shallow sequencing is a promising avenue for SM data analysis, detailed benchmarks using real-data are lacking. In this case study, we took four public SM datasets, one massive and the others moderate in size and subsampled each dataset at various levels to mimic shallow sequencing datasets of various sequencing depths. Our results suggest that shallow SM sequencing is a viable avenue to obtain sound results regarding microbial community structures and that high-depth sequencing does not bring additional elements for ecological interpretation. More specifically, results obtained by subsampling as little as 0.5 M sequencing clusters per sample were similar to the results obtained with the largest subsampled dataset for human gut and agricultural soil datasets. For an Antarctic dataset, which contained only a few samples, 4 M sequencing clusters per sample was found to generate comparable results to the full dataset. One area where ultra-deep sequencing and maximizing the usage of all data was undeniably beneficial was in the generation of metagenome-assembled genomes.


Assuntos
Metagenômica , Microbiota , Humanos , Análise de Sequência de DNA/métodos , Metagenômica/métodos , Metagenoma , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Microbiota/genética
10.
Mar Pollut Bull ; 174: 113288, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-35090274

RESUMO

Sea ice loss is opening shipping routes in Canada's Northwest Passage, increasing the risk of an oil spill. Harnessing the capabilities of endemic microorganisms to degrade oil may be an effective remediation strategy for contaminated shorelines; however, limited data exists along Canada's Northwest Passage. In this study, hydrocarbon biodegradation potential of microbial communities from eight high Arctic beaches was assessed. Across high Arctic beaches, community composition was distinct, potential hydrocarbon-degrading genera were detected and microbial communities were able to degrade hydrocarbons (hexadecane, naphthalene, and alkanes) at low temperature (4 °C). Hexadecane and naphthalene biodegradation were stimulated by nutrients, but nutrients had little effect on Ultra Low Sulfur Fuel Oil biodegradation. Oiled microcosms showed a significant enrichment of Pseudomonas and Rhodococcus. Nutrient-amended microcosms showed increased abundances of key hydrocarbon biodegradation genes (alkB and CYP153). Ultimately, this work provides insight into hydrocarbon biodegradation on Arctic shorelines and oil-spill remediation in Canada's Northwest Passage.


Assuntos
Microbiota , Petróleo , Bactérias/genética , Canadá , Hidrocarbonetos
11.
Sci Rep ; 11(1): 16203, 2021 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-34376730

RESUMO

Establishing low-error and fast detection methods for qubit readout is crucial for efficient quantum error correction. Here, we test neural networks to classify a collection of single-shot spin detection events, which are the readout signal of our qubit measurements. This readout signal contains a stochastic peak, for which a Bayesian inference filter including Gaussian noise is theoretically optimal. Hence, we benchmark our neural networks trained by various strategies versus this latter algorithm. Training of the network with 106 experimentally recorded single-shot readout traces does not improve the post-processing performance. A network trained by synthetically generated measurement traces performs similar in terms of the detection error and the post-processing speed compared to the Bayesian inference filter. This neural network turns out to be more robust to fluctuations in the signal offset, length and delay as well as in the signal-to-noise ratio. Notably, we find an increase of 7% in the visibility of the Rabi oscillation when we employ a network trained by synthetic readout traces combined with measured signal noise of our setup. Our contribution thus represents an example of the beneficial role which software and hardware implementation of neural networks may play in scalable spin qubit processor architectures.

12.
FEMS Microbiol Ecol ; 97(7)2021 06 18.
Artigo em Inglês | MEDLINE | ID: mdl-34124756

RESUMO

Douglas Channel and the adjacent Hecate Strait (British Columbia, Canada) are part of a proposed route to ship diluted bitumen (dilbit). This study presents how two types of dilbit naturally degrade in this environment by using an in situ microcosm design based on dilbit-coated beads. We show that dilbit-associated n-alkanes were microbially biodegraded with estimated half-lives of 57-69 days. n-Alkanes appeared to be primarily degraded using the aerobic alkB, ladA and CYP153 pathways. The loss of dilbit polycyclic aromatic hydrocarbons (PAHs) was slower than of n-alkanes, with half-lives of 89-439 days. A biodegradation of PAHs could not be conclusively determined, although a significant enrichment of the phnAc gene (a marker for aerobic PAH biodegradation) was observed. PAH degradation appeared to be slower in Hecate Strait than in Douglas Channel. Microcosm-associated microbial communities were shaped by the presence of dilbit, deployment location and incubation time but not by dilbit type. Metagenome-assembled genomes of putative dilbit-degraders were obtained and could be divided into populations of early, late and continuous degraders. The majority of the identified MAGs could be assigned to the orders Flavobacteriales, Methylococcales, Pseudomonadales and Rhodobacterales. A high proportion of the MAGs represent currently unknown lineages or lineages with currently no cultured representative.


Assuntos
Microbiota , Hidrocarbonetos Policíclicos Aromáticos , Poluentes Químicos da Água , Biodegradação Ambiental , Colúmbia Britânica , Hidrocarbonetos , Poluentes Químicos da Água/análise
13.
Microbiol Resour Announc ; 10(12)2021 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-33766906

RESUMO

Staphylococcus epidermidis is a common cause of implant-associated infections, and this is related to its ability to form biofilms. Strain-to-strain variability in biofilm formation is likely caused by genetic differences. Here, we present a draft genome of S. epidermidis AUH4567, which was isolated from a central venous catheter infection.

14.
Environ Microbiol Rep ; 12(2): 203-213, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31997572

RESUMO

The world's oceans are becoming increasingly polluted by plastic waste. In the marine environment, larger plastic pieces may degrade into nanoscale (<100 nm in at least one dimension) plastic particles due to natural weathering effects. We observe that the presence of 20 nm plastic nanoparticles at concentrations below 200 ppm had no impact on planktonic growth of a panel of heterotrophic marine bacteria. However, the presence of plastic nanoparticles significantly impacted the formation of biofilms in a species-specific manner. While carboxylated nanoparticles increased the amount of biofilm formed by several species, amidine-functionalized nanoparticles decreased the amount of biofilm of many but not all bacteria. Further experiments suggested that the aggregation dynamics of bacteria and nanoparticles were strongly impacted by the surface properties of the nanoparticles. The community structure of an artificially constructed community of marine bacteria was significantly altered by exposure to plastic nanoparticles, with differently functionalized nanoparticles selecting for unique and reproducible community abundance patterns. These results suggest that surface properties and concentration of plastic nanoparticles, as well as species interactions, are important factors determining how plastic nanoparticles impact biofilm formation by marine bacteria.


Assuntos
Bactérias , Biofilmes , Poliestirenos/farmacologia , Poluentes da Água , Organismos Aquáticos/efeitos dos fármacos , Organismos Aquáticos/crescimento & desenvolvimento , Bactérias/efeitos dos fármacos , Bactérias/crescimento & desenvolvimento , Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Nanopartículas , Oceanos e Mares , Plásticos/química , Plásticos/farmacologia , Água do Mar/microbiologia , Poluentes da Água/química , Poluentes da Água/farmacologia
15.
Proc Natl Acad Sci U S A ; 116(38): 19116-19125, 2019 09 17.
Artigo em Inglês | MEDLINE | ID: mdl-31427514

RESUMO

Cable bacteria of the family Desulfobulbaceae form centimeter-long filaments comprising thousands of cells. They occur worldwide in the surface of aquatic sediments, where they connect sulfide oxidation with oxygen or nitrate reduction via long-distance electron transport. In the absence of pure cultures, we used single-filament genomics and metagenomics to retrieve draft genomes of 3 marine Candidatus Electrothrix and 1 freshwater Ca. Electronema species. These genomes contain >50% unknown genes but still share their core genomic makeup with sulfate-reducing and sulfur-disproportionating Desulfobulbaceae, with few core genes lost and 212 unique genes (from 197 gene families) conserved among cable bacteria. Last common ancestor analysis indicates gene divergence and lateral gene transfer as equally important origins of these unique genes. With support from metaproteomics of a Ca. Electronema enrichment, the genomes suggest that cable bacteria oxidize sulfide by reversing the canonical sulfate reduction pathway and fix CO2 using the Wood-Ljungdahl pathway. Cable bacteria show limited organotrophic potential, may assimilate smaller organic acids and alcohols, fix N2, and synthesize polyphosphates and polyglucose as storage compounds; several of these traits were confirmed by cell-level experimental analyses. We propose a model for electron flow from sulfide to oxygen that involves periplasmic cytochromes, yet-unidentified conductive periplasmic fibers, and periplasmic oxygen reduction. This model proposes that an active cable bacterium gains energy in the anodic, sulfide-oxidizing cells, whereas cells in the oxic zone flare off electrons through intense cathodic oxygen respiration without energy conservation; this peculiar form of multicellularity seems unparalleled in the microbial world.


Assuntos
Proteínas de Bactérias/metabolismo , Evolução Biológica , Deltaproteobacteria/genética , Deltaproteobacteria/fisiologia , Genoma Bacteriano , Proteoma/análise , Sequência de Aminoácidos , Proteínas de Bactérias/genética , Ciclo do Carbono , Movimento Celular , Quimiotaxia , Citocromos/metabolismo , Deltaproteobacteria/classificação , Transporte de Elétrons , Sedimentos Geológicos/microbiologia , Nitratos/metabolismo , Oxirredução , Oxigênio/metabolismo , Filogenia , Homologia de Sequência , Sulfetos/metabolismo
16.
Microbiol Resour Announc ; 8(24)2019 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-31196919

RESUMO

Here, we present a 1.89-Mbp draft genome sequence of Streptococcus anginosus strain CALM001, a Gram-positive bacterium that was isolated from a fecal sample donated by a 70-year-old Dane enrolled in the Counteracting Age-Related Loss of Skeletal Muscle Mass (CALM) intervention study.

17.
Appl Environ Microbiol ; 85(10)2019 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-30850431

RESUMO

Western Canada produces large amounts of bitumen, a heavy, highly weathered crude oil. Douglas Channel and Hecate Strait on the coast of British Columbia are two water bodies that may be impacted by a proposed pipeline and marine shipping route for diluted bitumen (dilbit). This study investigated the potential of microbial communities from these waters to mitigate the impacts of a potential dilbit spill. Microcosm experiments were set up with water samples representing different seasons, years, sampling stations, and dilbit blends. While the alkane fraction of the tested dilbit blends was almost completely degraded after 28 days, the majority of the polycyclic aromatic hydrocarbons (PAHs) remained. The addition of the dispersant Corexit 9500A most often had either no effect or an enhancing effect on dilbit degradation. Dilbit-degrading microbial communities were highly variable between seasons, years, and stations, with dilbit type having little impact on community trajectories. Potential oil-degrading genera showed a clear succession pattern and were for the most part recruited from the "rare biosphere." At the community level, dispersant appeared to stimulate an accelerated enrichment of genera typically associated with hydrocarbon degradation, even in dilbit-free controls. This suggests that dispersant-induced growth of hydrocarbon degraders (and not only increased bioavailability of oil-associated hydrocarbons) contributes to the degradation-enhancing effect previously reported for Corexit 9500A.IMPORTANCE Western Canada hosts large petroleum deposits, which ultimately enter the market in the form of dilbit. Tanker-based shipping represents the primary means to transport dilbit to international markets. With anticipated increases in production to meet global energy needs, the risk of a dilbit spill is expected to increase. This study investigated the potential of microbial communities naturally present in the waters of a potential dilbit shipping lane to mitigate the effects of a spill. Here we show that microbial degradation of dilbit was mostly limited to n-alkanes, while the overall concentration of polycyclic aromatic hydrocarbons, which represent the most toxic fraction of dilbit, decreased only slightly within the time frame of our experiments. We further investigated the effect of the oil dispersant Corexit 9500A on microbial dilbit degradation. Our results highlight the fact that dispersant-associated growth stimulation, and not only increased bioavailability of hydrocarbons and inhibition of specific genera, contributes to the overall effect of dispersant addition.


Assuntos
Bactérias/metabolismo , Hidrocarbonetos/análise , Poluição por Petróleo/análise , Poluentes Químicos da Água/análise , Biodegradação Ambiental , Colúmbia Britânica , Água do Mar/análise
18.
Rev Sci Instrum ; 89(11): 114701, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30501331

RESUMO

Solid-state qubit manipulation and read-out fidelities are reaching fault-tolerance, but quantum error correction requires millions of physical qubits and therefore a scalable quantum computer architecture. To solve signal-line bandwidth and fan-out problems, microwave sources required for qubit manipulation might be embedded close to the qubit chip, typically operating at temperatures below 4 K. Here, we perform the first low temperature measurements of a 130 nm BiCMOS based SiGe voltage controlled oscillator at cryogenic temperature. We determined the frequency and output power dependence on temperature and magnetic field up to 5 T and measured the temperature influence on its noise performance. The device maintains its full functionality from 300 K to 4 K. The carrier frequency at 4 K increases by 3% with respect to the carrier frequency at 300 K, and the output power at 4 K increases by 10 dB relative to the output power at 300 K. The frequency tuning range of approximately 20% remains unchanged between 300 K and 4 K. In an in-plane magnetic field of 5 T, the carrier frequency shifts by only 0.02% compared to the frequency at zero magnetic field.

19.
Front Microbiol ; 9: 2038, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30233524

RESUMO

Desulfatiglans-related organisms comprise one of the most abundant deltaproteobacterial lineages in marine sediments where they occur throughout the sediment column in a gradient of increasing sulfate and organic carbon limitation with depth. Characterized Desulfatiglans isolates are dissimilatory sulfate reducers able to grow by degrading aromatic hydrocarbons. The ecophysiology of environmental Desulfatiglans-populations is poorly understood, however, possibly utilization of aromatic compounds may explain their predominance in marine subsurface sediments. We sequenced and analyzed seven Desulfatiglans-related single-cell genomes (SAGs) from Aarhus Bay sediments to characterize their metabolic potential with regard to aromatic compound degradation and energy metabolism. The average genome assembly size was 1.3 Mbp and completeness estimates ranged between 20 and 50%. Five of the SAGs (group 1) originated from the sulfate-rich surface part of the sediment while two (group 2) originated from sulfate-depleted subsurface sediment. Based on 16S rRNA gene amplicon sequencing group 2 SAGs represent the more frequent types of Desulfatiglans-populations in Aarhus Bay sediments. Genes indicative of aromatic compound degradation could be identified in both groups, but the two groups were metabolically distinct with regard to energy conservation. Group 1 SAGs carry a full set of genes for dissimilatory sulfate reduction, whereas the group 2 SAGs lacked any genetic evidence for sulfate reduction. The latter may be due to incompleteness of the SAGs, but as alternative energy metabolisms group 2 SAGs carry the genetic potential for growth by acetogenesis and fermentation. Group 1 SAGs encoded reductive dehalogenase genes, allowing them to access organohalides and possibly conserve energy by their reduction. Both groups possess sulfatases unlike their cultured relatives allowing them to utilize sulfate esters as source of organic carbon and sulfate. In conclusion, the uncultivated marine Desulfatiglans populations are metabolically diverse, likely reflecting different strategies for coping with energy and sulfate limitation in the subsurface seabed.

20.
Stand Genomic Sci ; 13: 10, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29686747

RESUMO

Here we present the genome of Methylovulum psychrotolerans strain HV10-M2, a methanotroph isolated from Hardangervidda national park (Norway). This strain represents the second of the two validly published species genus with a sequenced genome. The other is M. miyakonense HT12, which is the type strain of the species and the type species of the genus Methylovulum. We present the genome of M. psychrotolerants str. HV10-M2 and discuss the differences between M. psychrotolerans and M. miyakonense. The genome size of M. psychrotolerans str. HV10-M2 is 4,923,400 bp and contains 4415 protein-coding genes, 50 RNA genes and an average GC content of 50.88%.

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